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pickemup
Gen III
 
11/13/2003
14:40:32
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 Subject: Oil in wire harness/O2 sensor
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Message:
Hello,
I have been lurking in these forums for some time now and have learned some great stuff. I don’t know that I even qualify as a “Shade Tree Mechanic,” but I do as much of my own maintenance as possible, and fix things when I can.
I am now having a problem that is beyond my ability, and hope someone here can help. I also have learned something about Gen III Daks that I haven’t seen posted, so I hope I can help you all with a valuable heads up.
First the basics:
2000 Dakota Extended Cab 4X4
4.7 L V8
5 Sp
Stock
The truck has about 48,700 miles, and has had NO problems since new. It’s a New England commuter, so it doesn’t get abused.
It all started about two weeks ago when I changed the plugs for the first time. I put in Autolite 5224’s as widely recommended here. A couple of days later it stalled, and when restarted showed a Check Engine light. I pulled the code P0107, MAP Sensor. Thinking it had something to do with the plug replacement, I repeated the work I had done to make sure I didn’t inadvertently knocked something loose. I found that the passenger side cylinders were burning clean, but the driver’s side was very sooty indicating a way too rich mixture. Since the MAP sensor looks at the intake, which is shared by all cylinders, it made me think that the MAP sensor error was the result of the abnormal operation, not the cause.
I decide to check the driver’s side pre-cat 02 sensor, as it is the one feeding information to the computer for fuel mixture calculations. When I unhooked the O2 to engine harness connector I found oil in it. I cleaned the connectors and replaced the sensor with an aftermarket Bosch. Within about 20 miles of driving, the truck stalled and the code returned along with P0171.
Removing the O2 sensor, I again found oil in the connector. I have search the entire engine compartment area repeatedly, and find oil nowhere except on the INSIDE of the connector. I have repeatedly cleaned it, and it always returns. It appears to be flowing through the wires under the insulation, and has even found its way down into the splice housing on the new Bosch O2 sensor.
My dealer has been no help. Their computer says no reading on the O2 sensor and they insist the truck has to have a factory sensor. They replaced it and the replacement also filled with oil and died.
Here’s the part where I think I can help you all. I believe I have traced the oil back to a faulty pressure switch on the power steering pump! There was oil in that connector as well, and it looks and smells the same. When I brought this information back to my dealer, they admitted that they have seen the problem more than a few times.
I replaced the pressure switch ($18.00), and would recommend that you all consider this a regular maintenance item. Short money to avoid costly problems. The connector to the switch is now clean and dry, and the flow of oil to the O2 sensor connector appears to have slowed. It may take some time before it stops completely, now that the harness is full. My problem is that the engine is still showing P0171 and P0107 codes. After clearing the computer it takes 15-20 miles for the codes to reappear. The car sometimes hunts at idle, and occasionally stalls (always when decelerating), but otherwise runs o.k.. The drivers side cylinders are still running rich and the other side are fine. The exhaust smells bad as a result of the rich operation.
What should I be looking at next? The dealer has been no help. They are perfectly willing to just replace every part under the hood in the hopes of stumbling across the right one. Am I right in thinking this must be an exhaust rather than an intake problem? Could the oil have gotten into the O2 sensors themselves and ruined them. Has anyone used the Bosch replacements and found them acceptable? Could the above codes be the result of a bad cat? I see that there are a couple of TSB’s on 2000 Dak’s failing to properly diagnose catalyst problems, but don’t know the details.
Please help!
AR
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pickemup
Gen III
11/17/2003
21:28:14
|  RE: Oil in wire harness/O2 sensor
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Message:
No replies to my previous post?
O.K., perhaps it was a bit too long winded. How's this for a brief restatement?
What are the most likely causes of one bank of cylinders running rich, and the other bank running fine? I've already replaced the pre-cat O2 sensor on the rich side, without noticeable effect.
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pickemup
Gen III
1/14/2004
21:32:57
| RE: Oil in wire harness/O2 sensor
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Message:
The Power Steering Pressure Switch was the source of the oil. My problem was that by the time I had figured it out, the oil had already ruined the second 02 sensor installed by the dealer. I had to put in another one, and have now been driving two months without any problems.
Note to all 4.7L Dakota owners - Through my ordeal I have learned this is a somewhat common problem. Typically the dealer's recommended solution is to replace the engine harness for $1,700. I recommend that any time you're under the hood doing work, pull the connector to the pressure switch and check it for oil. The switch is an $18.00 part and takes two minutes to change. It's better to catch it before it takes out a $160.00 O2 sensor.
Now I am fighting with the dealership to try to get my money back. They replaced the 02 sensor without addressing the root cause of the problem, so that new sensor was ruined within three days. This is after I repeatedly pointed out the oil in the harness before they did the work! They admit the misdiagnosis and have agreed to reimburse me for the diagnostic charge, but they refuse to reimburse me for the sensor and the labor to install it.
Al
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Rob454
Dodge Dakota
JOIN HERE
1/15/2004
01:22:47
| RE: Oil in wire harness/O2 sensor
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Message:
Hey bro I e mailed you a few days ago. Since they screwed up you need to go over their heads. I would jsut either have your lawyer write them a letter or simply take them to small claims court. I had THE SAME thing happen to mine and they gave me the same 1700$ quote to which I laughed really really hard as I got back in my truck. Went back and told them I want my 500$ back. Since they havent fixed it and they are accepting responsability and even stating they misdiagnosed it, getting your $$ back should be a no brainer.
Good luck
Rob
Like I said if you need me to write a letter for the court Ill gladly do it cause I had the same problem and I was refunded my $$ back for the diagnosis, labor and O2 sensor.
I cant stand when someone is being unfair especially in business
Rob
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cab
Dodge Dakota
JOIN HERE
6/07/2004
15:11:08
| RE: Oil in wire harness/O2 sensor
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Message:
i'm getting an error code about my power steering pressure switch. Is this easy to change? I don't even know what it looks like.
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ccpower
Dodge Dakota
JOIN HERE
7/26/2004
13:19:02
| RE: Oil in wire harness/O2 sensor
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Sounds like I might be having the same problem. I am getting code 0171 and looking at the pre-cat o2 sensor on my 2000 4.7 liter, there is an oil film on the sensor. You can actually see oil burning off it. A few days ago I got another code indicating power steering pressure high, and the reservoir was on the low side. This is probably when the switch failed and I guess leaked into the harness. My question is why does an external oil leak cause the O2 sensor to fail?
JerryM
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ken olson
Dodge Dakota
JOIN HERE
9/27/2004
20:12:52
| RE: Oil in wire harness/O2 sensor
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I have experienced the same. My wiring harness is soaked with steering fluid. I, too laughed at the repair estimate. Local Dodge dealer wanted $2600 to replace the harnes and steering sensor. The truck is running and plan to replace the O2 sensor and steering pressure switch. I can replace a lot of O2 sensors for $2600.
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uhhu
Dodge Dakota
JOIN HERE
9/27/2004
22:32:05
| RE: Oil in wire harness/O2 sensor
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Message:
The oil leaking from the p/s switch probably wicked all the way down to the sensor itself. Chrysler says the o2 sensor is vented through the wiring of the sensor and cannot operate properly if that vent is restricted by dirt, oil ect. So replacement of the sensor is probably your best bet.
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